The present invention relates to the production of proteinaceous food products of a fibrous nature, and more particularly, to a process for preparing large chunks or loaves of protein having a meat like texture.
The food industry has, for many years, attempted to provide high protein, low cost fibrous proteinaceous material as a substitute for meat. This effort has been amplified recently due to the relative shortages and high prices for natural meat products. Early efforts to provide meat analog products were developed around a simplified model of natural meat which comprised a system of fibers held together by a suitable binder. To simulate the fibrous texture of natural meat, synthetic textile fiber technology was applied to the preparation of protein fibers which could be bound together to form a meat-like mass. A basic patent disclosing means of spinning proteinaceous fibers for meat analogs is Boyer, U.S. Pat. No. 2,682,466, issued June 29, 1954. Since then, numerous patents have issued employing similar proteinaceous fibers. Among these are U.S. Pat. No. 3,320,070 issued to W. E. Hartman, which discloses mixing vegetable protein fibers with an albumen binder and then heat setting. In another recent U.S. Pat. No. 3,772,035 to A. E. Carp et al., a process is disclosed for producing a meat analog by preparing a number of bundles of oriented spun protein fibers, impregnating these bundles with an albumen binder, heat setting the surface portions of these bundles, and then assembling the bundles for final coagulation under heat and pressure. While these spinning techniques have produced satisfactory meat analog products, they require extensive capital cost outlays and require high processing expenditures. Moreover, because the fibers are based upon soy protein, the resulting products are nutritionally deficient unless the distribution of essential amino acids is modified by suitable additives. Additionally, the more sophisticated and discriminating consumers were readily able to differentiate the texture of these products from chunks of natural meats.
Because of the inherent limitations associated with the meat analog products based upon spun protein fibers, other techniques for producing products of this type have been investigated. For example, in U.S. Pat. No. 3,047,395 to Rusoff, et al., there was disclosed an autoclaving process which eliminated the need for spun protein fibers. According to that disclosure, a protein slurry was rapidly heated under continuous agitation to cause coagulation of the protein into a fibrous mass. Rapid cooling of the protein resulted in a shred-like fibrous material which was recovered at rather low yield.
Further recent patents have disclosed methods based upon the extrusion of protein materials to develop a fibrous or fiber-like structure. The economies inherent in such processes were believed to outweigh any loss in fiber identity which these products might have as compared to the spun fiber analogs. By extruding larger fibrous materials, it was hoped that the need for binding the smaller segments could be eliminated. For example, the U.S. Pat. Nos. to Atkinson, 3,480,442 and 3,488,770, and to Jenkins, 3,496,858 suggest extruding vegetable protein material from an area of high pressure to an area of reduced pressure to produce an expanded mass or rope of proteinaceous material. The sudden expansion from high pressure to atmospheric pressure caused expansion in the direction of flow which produced the appearance of fibers.
A process capable of preparing a greatly improved fibrous product by extrusion is disclosed in U.S. patent application Ser. No. 309,301 filed Nov. 24, 1972 by A. Feldbrugge et al, now U.S. Pat. No. 3,886,299. According to this procedure, a highly-fibrous, substantially-unpuffed product simulating the muscle of animals or the flesh of fish is produced. That process calls for preparing a mixture containing above 35% by weight heat coagulable protein; adjusting the moisture content of the mixture to 25%- 65% water; blending the water and protein mixture to form a dough having a fibrous character when stretched; compressing the dough in a chamber wherein the volume of the channel between flights of the screw is decreased 2/1 or more from feed to discharge of the chamber to degas and densify the dough into a unitary body, said chamber formed by a heated outer wall and the channel of a rotating screw, said wall heated in excess of 250.degree. F.; simultaneously heating the dough and elongating the dough while the dough is under compression to a heat set, thermally-coagulated fibrous product having fiber alignment in the direction of the channel; releasing the compression on the product without forcing the product through a dye while maintaining a pressure drop below 100 psi thereby causing 20% or less puffing of the product and while maintaining the aligned fibrous condition of the product; and recovering the fibrous product. The disclosure of this application is hereby incorporated by reference. The present invention provides an improvement upon this process and provides a product which more nearly equals the textural characteristics of natural meat and fish.